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\begin{document}

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\twocolumn[
\Large 
\centerline {\bf STTR Phase~I Project Description}
\normalsize
\vspace{0.5cm}
]


\section{Identification and Significance of the Innovation}

Powerful and economical THz sources are key to realizing the full
potential of this emerging wavelength regime. In Phase~I of the STTR
TeraVision Inc. proposes to partner with the University of Arizona in
utilizing carbon  nanotube technology together with leading edge
micromachining to develop THz sources and amplifiers scaled from
proven traveling-wave tube designs. These tubes can be configured to
serve as  high power signal sources or low noise amplifiers, with
package sizes of the order of 10x10x10~cm. The availability of
such sources and amplifiers will help make THz imaging systems a
reality and unleash a wide variety of  applications. 

As THz detector technology has recently become more widely available, 
the number of potential THz applications has
skyrocketed. Potential THz applications range from the standoff
detection of explosives and chemical and biological agents, to the
measurement of in vivo tissue water content, fat content, blood
glucose and cholesterol contents and the diagnosis of cancer.  In
dentistry, THz imaging may provide a powerful alternative to X-rays. In
the food processing industry, THz waves will help detect E-coli and
other poisonous bacteria as well as small imperfections in
packaging. THz spectroscopic imaging can help Law-enforcement with the
detection of prohibited substances and counterfeit bank notes. 

Yet, despite all the exciting laboratory work, very few commercial
products have made it to market. Naturally occurring sources have very
limited THz power output, and artificial sources to date (far infrared
lasers, femto-second lasers, free electron lasers, synchrotron
particle accelerators etc.) have proven inadequate (too bulky, not
efficient enough, too expensive) for most Terahertz applications.  

\section{Background and Phase~I Technical Objectives}

Traveling wave tubes (TWT's) are a proven technology to frequencies of
$\sim$100 GHz. Indeed, these devices can be found in the majority of
communications satellites, ground-based and airborne radars, and a
variety of remote sensing systems. Our goal in Phase~I is to complete
a thorough design study for manufacturing TWT based oscillators and
amplifiers for operation in the THz frequency regime. The critical
components of a TWT are the cathode, beam focusing optics, slow-wave
structure, and collimating magnetic field. In the Phase~I design study
we will:

\begin{enumerate}
\setlength{\topsep}{-1ex}
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\setlength{\itemsep}{-0.4ex}
\setlength{\parsep}{-0.4ex}

\item Investigate the use of carbon nano-tube technology to provide
the electron source. 
\item Use state-of-the-art software tools to optimize 
\begin{itemize}
\item the design of electrostatic focusing optics to reduce the
electron beam diameter to the required size (10-50 microns) for THz
applications 
\item the interaction impedance between electron beam and the
electromagnetic field in the slow-wave structure.
\end{itemize}
\item Use the micromachining facilities at the University of Arizona
to fabricate prototype slow-wave structures. 
\item Use the electron microscope test-bed system at the University of
Arizona to verify performance of slow-wave structures. 
\item Use modeling and test results to investigate the feasibility of
  realizing commercial 368~GHz and 1.5~THz TWT amplifiers and oscillators. 
\end{enumerate}
  

The Phase~I report will include both modeling and experimental results
and provide a clear path to commercial applications. 
 
\section{Phase~I Research Plan}

\subsection{Traveling Wave Tube Amplifiers: Principle of Operation}

Traveling wave tube amplifiers are currently in use from below 1 GHz
to ~100 GHz and are capable of generating power levels from watts to
megawatts. They are used in a wide variety of applications; including
radar, communications satellites, and electronic countermeasure
systems.  Amplification occurs through an interaction between an
electron beam and a nearby radio frequency (RF) circuit carrying the
signal to be amplified. Through the interaction some of the kinetic
energy of the electrons in the beam is transformed into RF
radiation. For this to occur the velocity of the RF signal flowing
through the circuit must be slowed down to match the speed of the
electrons in the beam. The possibility of such an interaction was
recognized as early as 1933 (Haeff 1933, Lindenblad 1940) and later
Kompfner (1942) were the first to describe using a helical
transmission line wrapped around an electron beam as a tube
architecture that meets these requirements. The helix serves as the
slow-wave structure that matches the axial propagation velocity of the
RF signal to that of the electron beam. The basic design of such a TWT
is shown in Figure~1 (Gilmour 1994).  Today slow-wave structures
composed of coupled cavities also serve this purpose.  

\begin{figure}[!hbt]
\centering
\includegraphics[scale=0.3,angle=0]{./figures/Gilmour1.eps}
\caption{\label{gilmour1} {\small \it Schematic of an experimental helical
traveling wave tube (TWT), from Gilmour (1994). }} 
\end{figure}

When an electron beam is injected along the axis of the helix, axial
electric field components of the RF signal accelerate some electrons
while decelerating others. This interaction causes the electrons in
the beam to bunch-up.  As an electron bunch travels down the center of
the helix each interaction with the RF signal increases the charge
density in a given bunch. The fields produced by the bunching
electrons in the beam will induce corresponding electric currents in
the helix, adding constructively to the electric field of the signal
it is carrying. As the beam-wave interaction continues, the induced
waveform rapidly becomes larger than the initial signal and
amplification occurs (Gilmour 1994). A diagram illustrating the
relationship between electron bunch charge density and RF circuit
voltage with distance along the tube axis is shown in Figure~2 (Hess
1960).  

\begin{figure}[!hbt]
\centering
\includegraphics[scale=2.4,angle=0]{./figures/Gilmour2.eps}
\caption{\label{gilmour2} {\small \it Illustration of the interaction
    between electron beam and RF signal in a TWT, resulting in RF
    amplification. Adapted from Hess (1960) in Gilmour (1994).}} 
\end{figure}

Note that near the end of the tube the charge density in an electron
bunch becomes large enough for space-charge forces to begin to
disperse it, leading to destructive interference and field
saturation. Today the two most common types of slow-wave structures
used are the venerable helix and coupled waveguide cavities. The
helical design can generate tens to hundred of watts over as much as
two octaves of frequency. The coupled-cavity type TWT is narrower band
(10-20\%), but is capable of producing megawatts of power.  


\subsubsection{THz Slow-wave Structures}

The practical high frequency limit of TWT's was continuously pushed to
higher frequencies until the early 1990's when high frequency, high
electron mobility transistors (HEMTs) became available. Today,
HEMT-based amplifiers have been built to ~200 GHz, beyond which
limitations in photolithographic processing make them extremely
difficult (or impossible) to produce. The high frequency limit of TWTs
is set principally by losses in the slow-wave structure.  Using modern
machining and photolithographic techniques TWT operation to several
THz should be possible.  This plus the fact that TWTs have been shown
to be capable of very low-noise operation ($<$0.2 dB, Hammer and Wen
1964) provides a strong incentive to push TWT technology to higher and
higher frequencies.  

\begin{figure}[!hbt]
\centering
\includegraphics[scale=1.85,angle=0]{./figures/meandering1.eps}
\caption{\label{meandering} {\small \it 3D rendering of the geometry of a
    meandering waveguide slow-wave structure. }} 
\end{figure}

\begin{figure*}[!hbt]
\centering
\includegraphics[scale=0.4,angle=0]{./figures/twt_lab1.eps}
\hfill
\includegraphics[scale=0.4,angle=0]{./figures/twt_lab2.eps}
\caption{\label{twt_lab} {\small \it Left: Microscope image of TWT
amplifier slow-wave structure 
machined in the PI's lab at the University of Arizona. Right:
Interferometric Microscope image of the same structure. Measured
surface roughness is 120 nm rms waveguide depth is 352 \micron. }} 
\end{figure*}

The implementation of a helical slow-wave structure becomes more
difficult with frequency. Meandering waveguides have been successfully
used at high frequencies as an alternative slow-wave structure
(Figure~3).  Here interaction between beam and wave is maintained by
periodically folding the waveguide back into the beam path.  Sharp
corners in the bends should be avoided in order to reduce reflections
which reduce gain.  The waveguide cross section should be retained in
the bends for the same reason. Electron-signal interaction occurs
where the particle beam passes through the waveguide. The degree of
electron-beam interaction that takes place at each encounter is
described by the gain parameter $C$, given by (Pierce 1950):  


\begin{equation}
C = \left ({Z_{\circ} \over 4\,V_{\circ}/I_{\circ}} \right )^{1/3}
\end{equation} 

\noindent where $Z_{\circ}$ is the interaction impedance and $V_\circ/I_\circ$
is the beam impedance. Waterman (1979) successfully constructed a 46
GHz TWT using the meandering waveguide structure shown in above. For
this structure he derives a value of $Z_\circ = 4.65 \Omega$.  For our
proposed investigations we will use a 1/8$^{\rm th}$ scale of Waterman's design
implemented in a copper ``split-block'' ({\it J. Waterman has agreed to
collaborate with us on this project, see Support Letter}).  At the
design frequency of 368 GHz the characteristic dimensions of the
meandering structure are $G = 79.5 \; \mu$m, $W = 457 \; \mu$m, $L = 177
\; \mu$m , and $H=346 \; \mu$m, with a $127\mu$m diameter beam hole.
Using the high precision Kern micro-milling machine available in
the PI's  lab at the University of Arizona, we have fabricated this
split block structure (see Figure~4) and will test its performance in
the near future. 
   

In the initial characterization of the meandering slow-wave structure
we will use our electron microscope as the beam source (see
Figure~5). 
We will then replace the electron microscope with a compact, high
efficiency beam source that utilizes commercially available power
supplies, carbon nanotube cathodes (see section 3.1.2 below), and
permanent magnets (for beam confinement). Typical values of beam
current and voltage are $V_\circ = 25$ keV and 
$I_\circ = 1$~mA. Substitution into the above equation then yields a
value of $C= 0.0036$. The power gain $P_G$ of a TWT can be expressed
as  (Gilmour 1994): 

$$P_G = 47.3 \,C N\,{\rm dB}$$

\noindent where $N = {\rm tube \; length}/L$.  
To achieve $P_G$ of 10 dB will require a $N\sim 59$ and an overall
tube length of $\sim 1$~cm.

We have modeled the full length of the slow-wave
structure in CST Microwave Studio and found the total loss (including
the effects of finite conductivity, surface roughness and leakage
through the beam tunnel) to be $<$2~dB across the operating range of
the tube. A snapshot of a computer animation showing the propagation
of fields in the slow-wave structure is shown in Figure~6.  

\begin{figure}[!hbt]
\centering
\includegraphics[scale=0.32,angle=0]{./figures/uscope.eps}
\caption{\label{uscope} {\small \it Amray 1000a scanning electron
microscope to be used as an electron beam source in initial TWT
measurements. }}  
\end{figure}

\begin{figure*}[!hbt]
\centering
\includegraphics[scale=3.5,angle=0]{./figures/cst_sim.eps}
\caption{\label{cst} {\small \it CST Microwave Studio
simulation of the proposed design demonstrates low losses across the
full operating range of the TWT.  }}   
\end{figure*}

Predictions of $C$,  $Z_0$, and $P_G$ will be tested by real circuits and
beams in experiments with the modified SEM. Experimentally-determined
coupling impedances will then be used in large-scale TWT simulations
(see letter from Raytheon) to design optimized TWT circuit lengths and
parameters. Additional gain (up to $\sim$60~dB) can be achieved by
increasing the length of the slow-wave structure and/or raising the
beam current. As long as the beam can be confined to travel through
the beam tunnel and the surface roughness of the slow-wave structure
is $<$3 skin depths, the TWT circuit described here can be scaled
directly for operation at THz frequencies, giving it a huge advantage
over other devices.   

\subsubsection{ Electron Beam Source}

The primary goal in Phase~I will be to determine the feasibility of
producing a practical TWT device
at THz frequencies.  The electron beam of an SEM is a convenient,
flexible tool for experimentally verifying TWT performance. However,
a practical TWT must be designed to operate in a compact, efficient,
self-contained package. An important task in Phase~I will be to
design a new cathode based on low-power, low-temperature, carbon
nanotube field emitters.  Cathodes employing carbon nanotubes have
been demonstrated in a Northrop/Grumman TWT at 4.5~GHz
and require only 250V of gate voltage. At THz frequencies the size of
a unit such as this can be reduced by an order  of magnitude, making
them very attractive for a wide variety of applications.  Carbon
nanotubes may have the additional advantage of having exemplary noise
performance.  In 1964, Hammer \& Wen found that high-B fields applied
in the vicinity of the cathode reduced the transverse velocity
component in the e-beam, significantly  improving the noise
performance of the TWT.  Therefore nonthermionic emitters such as
carbon nanotubes may intrinsically provide better noise performance.  
 
\begin{figure*}[!hbt]
\centering
\includegraphics[scale=0.3,angle=0]{./figures/Einzel3DLine.eps}
\caption{\label{Einzel3DLine} {\small \it Electrostatic focusing of an electron beam from a carbon
nanotube cathode. }} 
\end{figure*}


Carbon nanotube gated electron sources are now commercially
available. One such source manufactured by Applied Nanotech Inc. can
generate the DC and AC beam currents of ~0.3 and 20 mA
respectively. Applied Nanotech has agreed to work with us ({\it see
  Support Letter})
to optimize their product for the proposed application. To work with
the proposed TWT the emitted electron beam must be focused to a spot
size of order 10 microns. We propose to use an einzel electrostatic
lens for this purpose (see Figure~7). Chang, Kern, and Murray (1990)
have successfully used similar lens configurations to create miniature
electron beam microscopes, directly analogous to our application
here. Compared to their magnetic counterparts, electrostatic lenses
are simple, compact, and take no power. An einzel lens contains 3
elements each with a through hole for the beam. The first and third
electrode are at the same voltage as the electron source gate. In our
preliminary design the through hole diameter is 1 mm and the third
(middle) aperture is at 200V relative to the other electrodes. This
geometry and voltage distribution electrostatically focuses a 1 mm
electron beam to approximately a few micron spot size over a 10 mm
distance. In our TWT application we place this focus just inside the
entrance to the beam tunnel in the slow-wave structure. Once in the
beam tunnel the solenoid (or permanent magnets) surrounding the
slow-wave circuit keeps the beam collimated. In Phase~I the design of
the electrostatic focusing system will be optimized using commercially
available software.  

\subsubsection{ Device Packaging}

The TWT itself must operate in a vacuum.  A 3D rendering of the
conceptual design is shown in Figure~8. 
Two power supplies are required; one for the
cathode itself and another to accelerate the electron beam to the
desired velocity ($\sim$0.3$c$). The power supplies are available
commercially from Ultravolt Inc. The gated, carbon nanotube cathode
with internal focusing can be purchased from Applied Nanotech Inc.,
who has agreed to work with us to achieve maximum performance from
their devices ({\it see letter of support from company}). The electron beam
is confined to travel in the beam tunnel by immersing it in a magnetic
field. For the beam characteristics described above, a magnetic flux
density of ~400 Gauss is required. Cylindrical, hollow permanent
magnets with this flux density are available from several vendors.  


\begin{figure*}[!hbt]
\centering
\includegraphics[scale=3,angle=0]{./figures/AmpAssembly.eps}
\caption{\label{Assembly} {\small \it 3D rendering of proposed THz TWT amplifier. }} 
\end{figure*}


The 368 GHz TWT will be designed to be scalable to higher
frequencies. As part of the Phase~I effort, we will design a 1.5~THz
version of the device. Laser micromachining technology is well suited
for the fabrication of the required THz waveguide structures. A 1~THz
meandering  waveguide TWT (Figure~9) was recently machined in the PI's
lab using a custom laser chemical etcher (LCE) system. This system
will be made available for the proposed effort. 

\begin{figure}[!hbt]
\centering
\includegraphics[scale=0.5,angle=0]{./figures/twt_umachined.eps}
\caption{\label{twt_umachined} {\small \it  1~THz meandering waveguide
structure laser micromachined in the PI's lab.  }} 
\end{figure}

In the implementation of a new TWT amplifier undesired backward-wave
oscillation (BWO) may occur, turning the amplifier into a source of
coherent radiation. BWO's can be significantly reduced or eliminated
by severing the slow-wave circuit. The two halves of the slow-wave
circuit remain reconnected by the electron beam which then induces an
amplified version of the input signal in the second half of the
circuit. If undesired BWO's are found to be present in the output of
the 368 GHz tube, we will add a sever. However, as described above,
there are many applications where a clean source of coherent THz
radiation is desirable. Therefore, as part of our investigation, we
will optimize a tube design to act as an oscillator.  

\subsection{ Traveling Wave Tube Oscillator}

In the standard BWO implementation some of the forward power is
reflected back along the slow-wave structure. In the case of the
meandering waveguide, Ohmic losses due to the long pathlengths would
have a negative impact on THz performance. However, Bhattacharjee et
al. (2004) have shown that recycling some of the forward power
directly back to the waveguide input may solve this problem. In their
paper the authors both model and test a 45 GHz TWT oscillator based on
this approach. In operation the TWTO passband showed that the device
had multiple frequency components in its output. Single frequency
operation could be achieved by adding enough attenuation in the
feedback loop so that only the strongest signal could get
through. There was no ability to set the TWTO to provide single line
operation at any other frequency. We will investigate the possibility
of adding frequency
selectivity to the TWTO by placing a micromachined, waveguide bandpass
filter in the return path. A 3D schematic of a frequency selective
TWTO is shown in Figure~\ref{FSSWO}.  

\begin{figure*}[!hbt]
\centering
\includegraphics[scale=3.2,angle=0]{./figures/FSSWO.eps}
\caption{\label{FSSWO} {\small \it  Schematic of proposed Traveling Wave Tube Oscillator (TWTO)  }} 
\end{figure*}

\begin{figure*}[!hbt]
\centering
\includegraphics[scale=3,angle=0]{./figures/OscAmpAssembly.eps}
\caption{\label{OscAssembly} {\small \it 3D rendering of proposed TWT Oscillator (TWTO).}} 
\end{figure*}

Using this approach, all the available power in the TWTO will be
funneled into the frequency of interest until saturation occurs, all
others frequencies are suppressed. By adjusting the width of the
sidewalls it would be possible to tune the filter and TWTO over a
significant frequency range, perhaps 20-30\%. The efficiencies
of TWT amplifiers are often better than 10\%.
Energy from the oscillator can be extracted from the
electron beam using the configuration shown in Figure~11.  



Here the output meandering waveguide is designed to provide 10 dB of
gain over what emerges from the oscillator. To avoid assembly
problems, the entire waveguide circuit can be machined at one time either
in copper (using Kern machine) or silicon (using the LCE system). An
Example of a 0.65 THz waveguide bandpass  filter (Kirby et al. 2003)
machined in the PI's lab is shown in Figure~12. 
 
\begin{figure}[!hbt]
\centering
\includegraphics[scale=0.4,angle=0]{./figures/BPF.eps}
\caption{\label{BPF} {\small \it THz  bandpass filters laser micromachined  in the PI's lab.}} 
\end{figure}


\subsection{ Precision Micromachining}

The TWT slow-wave circuits have structures that are small compared to
the design wavelengths. The ability to machine such structures at the
required size scale and accuracy has been a major hurdle in scaling
well--characterized structures from the microwave to THz spectral
regimes. With the aid of funds from the NSF, NASA, and Army Research
Office over the past decade, the PI's group at the University of
Arizona has established a micromachining capability uniquely suited to
making high quality waveguide and quasi-optical components to
submicron accuracies. The lab contains two custom-designed laser
micromachining systems. One system is optimized for making waveguide
devices from $\sim$0.8 to 5 THz. The second system is used to make similar
devices from $\sim$5 to 30 THz. In these systems the beam from an argon-ion
laser is focused onto a silicon wafer residing in a 200 Torr chlorine
ambient. The incident laser beam has enough power (typically several
watts) to vaporize a small volume ($\le$1~micron$^3$) of silicon that reacts
with the chlorine to make SiCl$_4$, which remains in the gas phase. Under
computer control the laser beam can be steered to create 3D
structures such as gratings or meandering waveguides (Drouet d`Aubigny
et al. 2004). Once the etching is complete, the etched silicon is gold
plated as needed to make it behave like normal waveguide or
quasi-optical structures.  A picture of one of the laser
micromachining systems to be used for the THz portion of the proposed
work is shown in Figure~13. 

\begin{figure}[htb]
\includegraphics[angle=0,scale=0.33]{./figures/lmc.eps}
\caption{\small \label{laser} \it Laser micro-milling machine in the PI's
  laboratory, used for fabrication of devices at frequencies $>$1~THz. } 
\end{figure}

\begin{figure}[htb]
\includegraphics[angle=0,scale=0.36]{./figures/kern.eps}
\caption{\small \label{kern} \it Kern micro-milling machine in the PI's
  laboratory, used for fabricating devices at frequencies $<$~1~THz. } 
\end{figure}

At frequencies below 1 THz the size of the structures to be etched
often require volumetric removal rates beyond the capabilities of the
laser micromachining systems. In order to fabricate such structures,
the PI's group has recently procured a state-of-the-art micro-milling
machine (KERN MMP 2522, see Figure~14) that can machine metallic and
ceramic structures to 1 micron precision and accuracy. This system
will be used to machine prototype 345 and 368 GHz TWT slow-wave
structures for the proposed effort, whereas the laser micromachining
system will concentrate on fabrication of 1.5~THz structures. 

The availability of these systems will permit the rapid prototyping
and optimization of the gratings and waveguide components needed for
this project, from microwave to THz spectral regimes.  


\subsection{ Plan of Action}

\begin{enumerate}
\setlength{\topsep}{-1ex}
\setlength{\partopsep}{-1ex}
\setlength{\itemsep}{-0.4ex}
\setlength{\parsep}{-0.4ex}


\item TWT Amplifier and Oscillator System Strawman Design (TeraVision Inc.)
\item Design and Modeling of prototype Slow Wave Structure (U of A)
\item Fabrication of 350 GHz Slow Wave Structure Split Blocks (U of A)
\item Design and  Fabrication of Anode (TeraVision Inc.)
\item Test in Raytheon SEM (TeraVision U of A)
\item Install Slow Wave Structure in SEM (U of A)
\item Turn Beam On and Measure amplification (U of A)
\item Procurement of Carbon Nanotubes (TeraVision Inc.) - Applied Nanotech Inc. and/or MER 
\item Design of Electrostatic Lens  (U of A)  
\item Electron Beam Characterization (I/V Curve / Beam size / Depth of focus/ power use / duty cycle/ pulse length etc.) (TeraVision Inc.)
\item Design Device Electronics (TeraVision Inc.)
\item Design Vacuum Vessel for Commercial Device (TeraVision Inc). Complete Integrated Package design (TeraVision Inc.)
\item Submit Phase~I Report with designs and feasibility studies for manufacturing 368 GHz and 1.5 THz TWT amplifiers and oscillators (TeraVision Inc.)
\end{enumerate}

\section{ Company Information}

\subsection{ Mission Statement and Company History}

TeraVision Inc was created in 2002 to bring THz expertise and enabling
technologies developed at the University of Arizona and MIT Lincoln
Laboratory to market. Soon thereafter, TeraVision Inc. licensed laser
etching technology from MIT.  More recently, the company has entered
into a Technology Transfer Agreement with the University of Arizona
for THz technology. Today, TeraVision Inc. maintains close ties to the
University of Arizona, and in particular Steward Observatory, the
Optical Sciences Center and the Department of Computer and Electrical
Engineering.  Our proximity to the University allows close
collaborations with distinguished researchers and access to the world
class facilities of a Research I Institution.  

\subsection{ Business Strategy}

As a small technology startup, TeraVision Inc.'s strategy is to
provide demonstrated THz technology platforms to established key
players in three main markets.  TeraVision has identified three
growing markets where the value of THz technology will justify the
initial cost of the new THz sources: Defense, Homeland Security, and
Medical Diagnostics. The company is identifying and forming strategic
partnerships with key players in those markets like Raytheon for
defense and homeland security, General Electric (InVision) for
homeland security and parts inspection and General Electric Health
Care for medical imaging and diagnostics. TeraVision is already
discussing partnership modalities with Raytheon Missile Systems and GE
and will be looking at partnering with other market leaders in the
near future. By developing the new THz source platform with help and
feedback from our end users and future customers, TeraVision expects
to have a Phase~II prototype that will not only meet the immediate
needs of the Department of Defense and the Air Force but will also
have a dual use platform technology readily portable to the medical
imaging.  Eventually as the technology matures and devices become more
affordable TeraVision will be ideally placed to serve the needs of
other industries where possible THz applications have already been
identified and tested in the laboratory. 

\subsection{ Relationship with Future Research or Research and Development}
The proposed STTR work matches the interests of both TeraVision
Inc. and Professor Walker's group at the University of
Arizona. TeraVision Inc. sees Phase~I of this STTR as an opportunity
to demonstrate the basic feasibility of the technology and develop a
basic working prototype. Working together with DoD prime contractors
like Raytheon, TeraVision Inc. anticipates it will have an early stage
commercial technology platform by the end of Phase~II. At that point,
the platform is expected to not only be immediately applicable to
Defense and Homeland Security programs, but also easily adaptable to
medical imaging and other industrial applications  
The present lack of THz sources constitutes a serious impediment for
development of large format heterodyne arrays for sub-millimeter
Astronomy which are at the core of Professor Walker's
research. Professor Walker has received funding from the NSF, NASA and
the US Army for the development of new THz detector technology. His
group has recently submitted a joint proposal to the NSF with Raytheon
Missile Systems to study radically new approaches to THz source
technology. The proposed research at the University of Arizona will
leverage resources established by previous government funding as well
as the new NSF and Raytheon funding, if awarded. 

\subsection{ Company Size and Revenue}

TeraVision Inc has no revenues and no employees. One of us (Christian
d'Aubigny), will join the company's employ if the proposal is
awarded. TeraVision Inc. is actively marketing laser micro-fabrication
technology and seeking both federal and private funding to develop new
THz sources. The proposed work would allow the company to accelerate
the development of a prototype source. 

\section{Commercial Potential }

\subsection{Suggested and Demonstrated Use of THz Radiation}

Terahertz technology has potential applications in the military sector
for standoff detection of chemical and biological agents and
enhancement of satellite communications. In the commercial sector, the
technology has applications in the security market (for detection,
identification and interrogation of explosives, chemical and
biological agents), medicine (measurement of in vivo tissue water
content, fat content, blood glucose and cholesterol contents and the
diagnosis of cancer), dentistry (as a powerful alternative to x-ray
images), pharmaceutics (real time, non-destructive chemical analysis
for quality control during drug fabrication), food processing
(detection of E-coli and other poisonous bacteria as well as detection
of small imperfections in packaging), and Law-enforcement (detection
of prohibited substances and of counterfeit bank notes). 

\subsection{ Supporting Market Data}

\subsubsection{Defense Market}

US Defense electronics market is expected to be worth \$181 Billion
over the next decade (source: The Forecast International Overview).
Practical applications of terahertz wave technology to Department of
Defense programs such as the Air Force are numerous.  For example, THz
wave technology will allow smaller radar antennas to yield more
detailed images. Also, THz remote sensing can be used to observe index
of refraction inhomogeneities caused by the ionization of air
molecules by radioactive materials.  In addition, they are sensitive
enough to determine whether a nuclear plant is active. Terahertz
technology also has potential applications in the military sector for
standoff detection of chemical and biological agents. THz satellite
communication will expand available bandwidth. Another advantage of
THz wave technology is the increased directivity of the beam which
will minimize signal interception and radar visibility.  

\begin{figure}[htb]
\includegraphics[angle=0,scale=0.27]{./figures/budgetfig1.eps}
\caption{\small \label{budget } \it Source: Congressional Budget Office. FYDP Future Years Defense
 Program, RDT\&E Research Development and Evaluation.} 
\end{figure}
 

\noindent {\it DoD Prime Contractors}: Lockheed-Martin, Boeing,
Northrop-Grumman, Raytheon, TRW, Mitre Corporation, United
Technologies, Science Applications International. 

\subsubsection{Security Market}

\noindent \underline{Chemical \& Biological Agent Detection Market}

\medskip

\noindent Passive and remote detection technologies utilized for the detection
of chemical warfare 

\smallskip

\noindent Agents include: Fourier transform infrared (FTIR), RAMAN infrared (IR)
spectroscopy, Active Laser Imaging Detection Ranging (LIDAR),
Interrogation (experimental) 
\smallskip

\noindent Point detection for the field or site monitoring technologies
includes: Ion mobility spectrometry (IMS), Field ion spectrometry
(FIS) (Russian, coaxial), Gas chromatography (GC), capillary column,
Mass spectroscopy  
\smallskip

\noindent Standoff detection of possible biological aerosols is much more
problematic than FTIR for chemical agents, although active lasers
(LIDAR) scanning for atmospheric anomalies are already fielded by the
U.S. Army. A combination of off-the-shelf instruments is used in the
point detection of biological warfare agents: Flow cytometry, 
Aerodynamic particle sizing, Antigen/antibody reaction, ATP-Luciferase
tests, Pyrolytic mass spectroscopy, DNA probes (developmental) 
\smallskip

\begin{figure}[htb]
\includegraphics[angle=0,scale=0.34]{./figures/marketfig1.eps}
\caption{\small \label{market } \it } 
\end{figure}
 


\noindent {\it Leading Participants}: 
The leading market participants (in terms of
revenue) in the world markets for chemical warfare agent detectors
include: Graseby Dynamics, Ltd. Intellitec (formerly Brunswick
Defense), Powertronic Systems, Lockheed Martin. The leading market
participants (in terms of revenue) in the world markets for biological
warfare agent detectors include: Hunting Engineering, Camber
Corporation, QTL Biosystems, Intellitec. 

\bigskip

\noindent \underline{Explosives Detection Systems Market}

\medskip

The Transportation Department recently announced plans to use a
combination of Explosives Detection Systems (EDS) and much less
expensive and easier to deploy trace detection systems (TDS). It is
expected that the deployment of EDS systems take place in two
phases. In the first wave, freestanding EDS units will be installed in
airport terminal lobbies.  In a second wave, EDS equipment will be
integrated into the airline baggage handling systems. Based on current
government procurement plans, the equipment cost for EDS deployment
alone is around \${\bf1.5 billion}. The international market opportunity is
nearly as large (source: Needham \& Company). 

\smallskip

\noindent {\it Leading Participant}: 
GE InVision Technologies (90\% market share)


\subsubsection{ Medical Imaging Market}

Due to several advantages over traditional imaging methods, THz
radiation has great potential in the field of medical imaging.  THz
radiation is non-ionizing and its use is intrinsically safer than
X-ray. In addition, THz radiation provides more detail than
conventional imaging methods such as X-ray and Ultrasound.  THz
radiation can be used to measure tissue water content and fat tissue
content, blood glucose and cholesterol levels. THz imaging can
accurately differentiate between malignant and benign skin disease and
diagnose skin cancer. This technology is likely to replace expensive
and invasive biopsy procedures in use at the present time.  

The medical imaging market is forecast to grow 7.6\% through 2008. It
includes the following modalities and equipment: 

\begin{itemize}
\setlength{\topsep}{-1ex}
\setlength{\partopsep}{-1ex}
\setlength{\itemsep}{-0.4ex}
\setlength{\parsep}{-0.4ex}

\item X-Ray Mammography
\item Positron Emission Tomography (PET)
\item Magnetic Resonance Imaging (MRI)
\item Gamma Cameras
\item Digital Radiography
\item Computed Tomography (CT)
\item Picture Archiving and Communications Systems (PACS) 
\item Osteoporosis Diagnostic Imaging Equipment
\item 3D Imaging
\item Ultrasound Imaging Equipment
\end{itemize}

%Market Size:

\noindent {\it Leading Participants}:
Agfa Healthcare, Canon Medical Systems, Eastman
Kodak, Fujifilm Medical, GE Medical Systems, Philips Medical Systems,
Siemens Medical Solutions, Toshiba Medical, Columbia Scientific, B-K
Medical, Fischer Imaging, Hologic, Instrumentarium Imaging, Konica
Medical Systems, Planmed, Shimadzu Swissray. 

\subsection{ Intellectual Property}

We plan to seek patents for any new devices developed under this STTR
through the University of Arizona.


\section{ Consultants and Subawards / Subcontracts}

TeraVision has also arranged for John Waterman to serve as a
consultant for this project. Mr. Waterman's pioneering thesis work at
Stanford University focused on high frequency TWT design and
fabrication. He then worked at Raytheon on high power millimeter wave
TWT. John Waterman now works for Brillian Corporation in an unrelated
field, and will be able to provide TeraVision with both theoretical
and hands-on help.  


\section{Equivalent or overlapping Proposals to other federal
agencies}

\begin{enumerate}

\item
\noindent U.S. Air Force, Air Force Research Lab, Wright-Patterson Air Force Base, Ohio. 

\noindent The Air Force STTR Program Manager is Mr. Steve Guilfoos, (800) 222-0336. 

\noindent Proposal Submitted on 04/15/2005

\noindent AF05-T020 ``Novel Terahertz Sources for Advanced Terahertz Power'', in STTR solicitation issued 02/01/2005

\noindent Nanoklystrons and nanoTWTs and date of solicitation

\noindent Novel Sources of Terahertz Power: Nano-Cathode Resonant TWT 

\noindent The proposed period of performance for this proposal is 10/01/05-06/30/06 actual performance period will depend on funding agency.

\noindent P.I. Professor Christopher Walker

\noindent Co.I. Christian Drouet d'Aubigny - Commitment 700 Hours (~4 person month) over a 9 months period. 

\medskip

While the work proposed here and the US Air Force proposal above are
in the same general area of research, their focus are different. The
work proposed to the Air Force focuses on making very compact, highly
efficient, low power, resonant sources. The work proposed here aims at
developing very high current density electron beams, focus and contain
them, and design high frequency microwave structures that will amplify
or produce very high THz power levels. While the two proposed efforts
would benefit from each other, we believe the scope of the work
proposed here is significantly different from that proposed to the Air
Force.     

\item
      
 \noindent National Science Foundation:  Electrical and Communications
Systems

\noindent            Proposal Title: THz Radiation Production and Amplification
Using a New Generation of Electron Beam Devices

\noindent            NSF Proposal No.: 0524785

\noindent            NSF Program Officer: Kawthar, A. Zaki,  ph.703-292-8339

\noindent            Total Award Amount: \$680,899 Total Award Period
           Covered: 08/01/05 - 07/31/08

\noindent           Location of Project: The University of Arizona

\noindent           Person-Months per Year of PI-Walker Committed to
             the Project: Sumr: 1.0

\noindent          PI: Christopher K. Walker

\noindent          Co-PI: Christian Drouet d'Aubigny (participation would be
                         reduced to zero, if pending STTR  
                         proposals with TeraVision Inc. are selected.)
 
The above proposal was submitted by the University of
Arizona to the NSF, there was no TeraVision Inc. participation. The
proposal outlines a program of fundamental research into generating THz
radiation through the Smith-Purcell effect and amplifying THz radiation
with TWT's. The research program does not seek to produce a commercial
device. 

\end{enumerate}
 
\end{document}
 


